22 March 2013
Women's lives at risk as they stop taking breast cancer treatment too early
Women with breast cancer who are prescribed tamoxifen or aromatase inhibitors after initial treatment are struggling to take medication
for the full five year duration, which increases their chance of cancer returning and their risk of dying.
Findings by Breast Cancer Campaign funded researcher Dr Colin McCowan (University of Glasgow with colleagues from the University of
Dundee) released in the British Journal of Cancer today, showed that at least half of women who were prescribed a five year course of
anti-hormone breast cancer treatment, in Tayside, Scotland, either stopped taking, or took markedly less than their prescribed doses from
the third year of treatment onwards. Women who followed their treatment regime for up to three years but then took fewer than 80% of their
pills in the fourth and fifth years were at a higher risk of their cancer returning, and of dying from breast cancer, than women who took
over 80% of the prescription over each of the five years.
Dr McCowan and his team at the University of Dundee studied the anonymised details of 3,361 women in Tayside who were prescribed
anti-hormone treatments tamoxifen or aromatase inhibitors for five years after their initial treatment. This is the current standard
treatment for women with the most common type of breast cancer, oestrogen receptor positive, which accounts for around 40,000 of the 50,000
diagnosed with the disease each year in the UK. These women started taking tamoxifen (2849 women) or an aromatase inhibitor (512 women)
between 1993 and 2008.
Using prescription records, researchers calculated how closely women had followed the "one a day" pill regime and for how long, over the
full five year treatment duration and also by year. If women had collected less than 80% of their prescription they were classed as having
a "low adherence" to their treatment.
They found that during the first year of treatment women collected, on average, 90% of their tablets. Over the next three years this
figure dropped to 82%, 77% and 59% respectively. By year five half of the women were collecting 51% or less of their prescription.
The study also confirmed previous findings that women who collected less than 80% of their prescription over the whole five years were
more likely to die earlier, than women who collected more of their prescription.
Breast Cancer Campaign researcher, Dr McCowan, said, "This study shows us that it's vitally important that breast cancer patients across
the UK follow their prescribed treatment regimes on a daily basis for the full five year period.
"We're now looking at why women are finding it harder to take medication for extended periods of time and we do know that side effects
can be a real issue for women on long term treatments such as tamoxifen. This is why women need the support of their clinicians so that they
can discuss any problems they are having rather than stopping taking treatments."
Baroness Delyth Morgan, Chief Executive of Breast Cancer Campaign said, "Breast cancer treatments are there to give women the best chance
of a long and full life after a diagnosis so these findings are hugely worrying. We need to give women clear, helpful and timely
communication as well as the best clinical support we can, to find ways to manage what can often be extremely difficult side effects and
make it easier for them to continue to take treatments. Taking tamoxifen for ten years has recently been recommended as one of the ways to
prevent more breast cancers returning and reduce the chance of women dying so it's going to be even more important to help women to take
drugs for longer periods of time.
"At Breast Cancer Campaign a key part of the research we're funding is to bring about new and improved, personalised treatments that
have fewer side effects as well as finding ways to identify early which treatments will work best for which patients."
Notes to editors
About Breast Cancer Campaign;
- Breast Cancer Campaign aims to beat breast cancer by funding innovative world-class research to understand how breast cancer develops, leading to improved diagnosis, treatment, prevention and cure
- The Breast Cancer Campaign Tissue Bank, the UK's first ever national breast cancer tissue bank is a unique collaboration with four leading research institutions to create a vital resource of breast cancer tissue for researchers across the UK and Ireland. Visit breastcancertissuebank.org
- The charity currently funds 95 projects worth more than £16.2 million in 34 locations across the UK and Ireland
- Breast cancer is the most common cancer in the UK and accounts for nearly one in three of all cancers in women
- In the UK, around 50,000 new cases of breast cancer are diagnosed each year - that's 136 a day
- Visit breastcancercampaign.org or follow us at twitter.com/bccampaign
About the British Journal of Cancer (BJC)
The BJC is owned by Cancer Research UK. Its mission is to encourage communication of the very best cancer research from laboratories and
clinics in all countries. Broad coverage, its editorial independence and consistent high standards have made BJC one of the world's
premier general cancer journals. www.bjcancer.com
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University of Dundee
Nethergate, Dundee, DD1 4HN
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E-MAIL: r.isles@dundee.ac.uk
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